Core plug



Jan. 2,1968 J. R. DORMAN 3,361,288

CORE PLUG Filed Feb. 25, 1966 Z4 Z5 INV TIOR.

I:'5I..5 kw? nmdmizum ATTORNEYS.

United States Patent 3,361,288 CORE PLUG Jack R. Dorman, 5757 MariemontAve, Cincinnati, Ohio 45227 Filed Feb. 25, 1966, Ser. No. 530,135 8Claims. (Cl. 22024.5)

This invention relates to core plugs. These plugs are employed to closeand seal the holes that are required in cast internal combustion engineblocks in order to remove the material used in the casting process toform the internal channels for coolant fluids. The locations of theseholes in the engine block primarily are dictated by foundry practicesand they often are located such that it is difficult for a mechanic toreplace one should this be required. Leakage or even loss of a plug isnot uncommon, and at times it is necessary for a mechanic to remove anumber of engine parts in order to gain access to a leaky plug. Theremoval and replacement of the plug itself is a matter of minutes butthe removal and replacement of engine parts in order to gain access tothe plug may take many hours.

This invention is directed to a core plug that makes it unnecessary toremove engine parts in order to replace a faulty core plug.

In general there are two types of core plugs that have been used in thepast as original equipment and as replacement equipment. One is ashallow cup, the walls of which are tapered slightly so that the cup maybe press fitted into the core hole and held therein by friction. Toreplace a cup type core plug there must be a substantial amount of spaceavailable to accommodate a tool such as a hammer by which the plug maybe driven or forced into the core hole. Another type is a disk that isconcave on that face Which is placed into the core hole and convex onthat face which is to the outside. The disk type plug is locked in placeto close and seal the opening by striking it with a tool such as ahammer to flatten it and thereby expand it radially. Here again it isimpossible to properly fit a plug of this type unless there is ampleroom to manipulate the fitting tool.

In the core plug of this invention the plug is adapted to be held orinitially fitted within the core opening by means such as a wrench andthen expanded to close and seal the opening by means of a second Wrench.These two wrenches do not necessarily have to approach the plug locationfrom the same direction and it is found that even though a core openingbe virtually inaccessible to a persons hand, the opening can be reachedfirst by the wrench that is used to initially place the plug in the coreopening and then the plug expanded by a second wrench, preferably aratchet type Wrench that is adapted to be manipulated in close quarters.

In the case of a leaky plug that is in an inaccessible location it isfound that it can be removed by driving a sharp instrument into it andthen prying it from the hole. This requires little space and theapproach can be made from any direction and removal presents no problem.Further, in the past it has been the practice to clean out the coreopening before replacing a plug and then to use a sealing compound thatis applied to those surfaces contacted by the plug. In order toaccomplish the cleaning and the application of a sealing compound itrequired that there be a sufliciently large enough opening to the corehole to permit a mechanic to get his hand to the hole. This is notnecessary with the plug of this invention because it can be expanded tosuch an extent and with such force that metal of the plug actually flowsto fill scoring marks and such intimate contact is made with the Wall ofthe opening that no sealing compound is required to prevent leakage.This is particularly important in modern automobile engine blockswherein pressures of up to and beyond 14 pounds per square inch of thecoolant fluids are developed. In actual test the plug of this inventionwas found to withstand internal pressures as high as 70 pounds persquare inch, indicating the intimacy of the seal and the radialpressures developed within the plug.

Thus, the primary objective of this invention has been to provide a coreplug that can be used to replace leaking or missing core plugs that arelocated in diflicult to reach places in an internal combustion engineblock.

Another objective has been to provide a core plug that is adapted towithstand substantially greater internal pressures than plugs of thepast and to require no cleaning of the surface of the core opening or asealing compound upon the plugs being set in place.

One cause for core plug failure has been the electrolytic action thattakes place in certain types of fluids where two different metalscontact one another. It has been another objective of this invention toprovide a core plug of the type set forth wherein the corrosive effectsof electrolysis is inhibited to an extent that it is failure free underconditions wherein plugs of the past would have been destroyed.

Because the plug of this invention is designed to be utilized in placeswhere it cannot be closely inspected, it has been a further objective toprovide a means of indicating to a mechanic the amount that the plug isexpanding while an installation is being made. Toward this end the plugis designed to expand predetermined amounts depending upon the number ofturns that are given an acorn nut by means of the wrench that isemployed to expand the plug. This same relationship is adapted to bebuilt into plugs of different sizes so that a mechanic knowing this canuse the same installation techniques for plugs of all sizesincorporating the principles of this invention.

These and other objectives and advantages of the invention will bereadily apparent to those skilled in the art from the following detaileddescription of the drawings in which FIGURE 1 is a side elevational viewof a core plug shown installed in the wall of a portion of an engineblock that is illustrated diagrammatically only.

FIGURE 2 is a side elevational view showing the four basic partscomprising the plug of this invention.

FIGURE 3 is an elevational View showing the outer face of the plug ofFIGURE 1.

FIGURE 4 shows the inner face thereof.

FIGURE 5 is an enlarged cross sectional View taken on a plane throughthe longitudinal central axis of the plug.

Referring to FIGURE 2, the plug consists essentially of an outer shell10, a brace or stiffener disk 11, an expander disk 12 that comprises anassembly in combination with a large headed bolt 13 and an acorn nut14-.

The shelllll, in the preferred embodiment, is made of a soft copper thatis capable of flowing under high pressures of the type that can bedeveloped during an installation of the plug of this invention. Itincludes a rim portion 15. It is preferred, although unnecessary, thatthis rim be given a slight taper in order to assist the initialinsertion of the plug into a core opening. The outer face of the plugshell is configuratcd as shown at 16 to provide a hexagonal projectionto receive the jaws of a wrench. The annular area between the hexagonalprojection of the rim portion 15, which is identified by the numeral 17,is formed as an integral part of the shell so that the shell is unbrokenexcept for a central opening shown at 18 in FIGURE 5 through which thethreaded shank 19 of bolt 13 may project. The outer face 2% of thehexagonal projection 16 of the shell is flat and, since the shell ismade of a relatively soft copper material, this portion of the shellacts as the equivalent of a copper washer when the acorn nut 14 istightened snugly in place against the face 2d at the time of aninstallation, thereby providing a seal to prevent leakage at this point.Also, as will be seen, there is little chance of leakage from the insideof an engine block to this point.

The brace disk 11 is the backbone of the plug and it must besufiiciently strong to absorb the stresses that are developed within theplug. It is found that a material such as 13-gauge steel works well forthis disk. By contrast, the copper shell may be as thin as 0.05 inch.The disk 1'. is configurated to rest within the copper shell ltl so thatit presents an annular face 2 1 to the rear surface of that area of thefront face 2% of the hexagonal projection against which the acorn nut 14is tightened at the time of installation. Thus, the outer annular area22 of the brace disk is offset inwardly with respect to the annularbackup portion 21. The disk 11 is of a diameter such that its rim 23fits the inner surface of the rim portion of the shell in slipfitrelation.

The expander disk 12 is made of a material such as 16-gauge steel and itis adapted to be seated within the rim portion 15 of the copper shelllid in slipfit relation, presenting its rim 24- to the inside surface ofthe rim portion 11 and making contact with the rim 23 of the brace disk11. Preferably, the expander disk 12 is just slightly larger in diameterthan the bracer disk 11.

Bolt 13 has a large flat head 25. That portion of the bolt immediatelyinside of the head designated 26 is splined and it is of a diameter suchthat when it is pressed into a central hole 27 in the expander disk, anexceedingly tight juncture is made. It is preferred that this joiningoperation be made under high pressure in order to achieve a fit in whichthe metals of the expander disk and the shank portion 26 of the boltWeld to one another.

Both the plug expander and the bolt in its entirety are copper plated inorder to resist the corrosive effects of the coolant fluids within theengine plug. It is preferred that a substantially thick plating be usedand this plating of the splined area 2 5 and the central hole 27 throughwhich the bolt passes ensures that an exceedingly intimate seal beachieved between the bolt and the expander disk.

With the parts of the plug assembled as shown in FIG- URE 5 thehexagonal projection 16 is placed in the jaws of a wrench. It ispreferred that the wrench used be one that can be adjusted to a pointwhere plug assembly may be manipulated by the wrench. The plug is theninserted into a core opening, as illustrated in FIGURE 1, of the wall ofan engine block shown diagrammatically only at 28, the broken sidedesignated 29, indicating the wall of the cavity inside of the engineblock. As is the usual practice, a shoulder 30 is provided within theopening. The plug is inserted until the rim 15 of the shell contactsshoulder 3%. At this point the acorn nut i i is engaged by a secondwrench, preferably a ratchet wrench. At this time the plug is looselyengaged in the core Opening. However, by holding it in place with thewrench engaged on the hexagonal portion 16, the ratchet wrench may beworked without having the plug turn within the hole and this iscontinued until the expander disk 12 is warped toward its being astraight disk to a point where intimate contact is achieved bet-ween rim15 and the wall of the core opening. At this point the first Wrench isno longer required and expansion of the plug can be continued by the useof the ratchet wrench only. It is found that in a plug wherein a 1.63diameter size is required (which is undersize with regard to the openingof a core hole) and wherein an expander disk is employed that is 1.54inches in diameter and of 16-gauge steel and curved on a radius of 2%inches and further wherein inch standard threads are employed for bolt13, the first complete turn of the acorn nut expands the plug 0.007inch. The second complete turn of the acorn nut is found to cause anadditional 0.011 inch of expansion. The third complete turn of the acornnut causes an additional 0.007 of an inch of radial expansion. It ispreferred that the nut be so designed that it bottoms at this point toprevent unknowing mechanics from building up excessive stresses Withinthe plug. The reason that the third turn causes a decrease in the amountthat the plug expands is because at this point there is so much pressureon the rim 15 of the copper shell that there is a substantial amount ofmetal flow axially. In actual practice no more than two turns of theacorn nut have been found to be required, most installations requiringonly one or just slightly more than one. In any event, by having therelationships described for the various parts it is possible for themechanic to know to within a few thousandths of an inch the exact amountof expansion that has occurred simply by his observing the number ofcomplete turns made by the acorn nut. Obviously, this relationship canbe built into plugs of various diameters.

It will be noted that in the preferred embodiment the bracer diskabsorbs the stresses that are placed upon the shell by the tightening ofthe nut and that it also absorbs the forces placed upon its rim by theexpander disk such that no undue stresses are placed upon the relativelythin copper shell 10.

Having described my invention I claim:

1. A core plug assembly adapted for use in core holes that are indifficult to reach locations on engine blocks, said plug comprising ashell having a circular rim portion and an outer face portion,

said rim portion initially being of a diameter that is slightly smallerthan a core hole in which the plug is to be used,

the outer face of said shell having a projection thereon that isconfigurated to receive a tool by means of which said assembly may beheld and manipulated,

an expander disk that is of a diameter to initially fit within said rimportion in slipfit relation,

said expander disk being concave and adapted to be seated within saidrim portion with the concave face thereof toward such shell portion,

a brace disk adapted to be seated within said shell between saidexpander disk and the outer face portion of said shell,

said brace disk having a central portion adapted to contact the rearface of the central portion of said projection and having an outerannular area adapted to contact that part of said outer face portionsurrounding said projection,

there being a central opening in said expander disk, said brace disk andsaid outer projection,

a large headed bolt extending through said expander disk, said bracedisk and said outer projection, said bolt having threads thereon,

and an acorn nut adapted to be engaged upon said threads such that thetightening of said nut causes said expander disk to be deformed radiallyoutwardly for expanding said rim portion into intimate contact with thewall of a core hole.

2. A core plug assembly as set forth in claim 1 in which said shell ismade of copper and said expander disk and said bolt are plated withcopper.

3. A core plug assembly as set forth in claim 1 in which the degree ofexpansion of said expander plug is directly related to the number ofturns given the acorn nut upon the tightening thereof.

4. A core plug assembly as set forth in claim 2 in which the projectionon said shell has a flat face in the area thereof against which saidacorn nut engages upon the tightening thereof, whereby said flat areaserves as a copper washer to provide a seal.

5. A core plug assembly as set forth in claim 1 in which said brace diskis more resistant to deformation than said expander disk.

6. A core plug assembly as set forth in claim 1 in which said shell isof soft copper and adapted to flow under high pressures.

("3 7. A core plug assembly as set forth in claim 1 in References Citedwhich said projection is hexagonal and adapted to receive UNKTED STATESyATENTS Wrench- 2,996,214 8/1961 Kemble 220-245 3. A core plug assemblyas set forth in claim 1 1n 3,175,727 3/1965 PM 220M245 which said boltbot-toms in said acorn nut prior to the 5 I expander disk being deformedto its maximum radial THERON CONDON Y EMYTWW- expansion. G. T. HALL,Examiner.

1. A CORE PLUG ASSEMBLY ADAPTED FOR USE IN CORE HOLES THAT ARE INDIFFICULT TO REACH LOCATIONS ON ENGINE BLOCKS, SAID PLUG COMPRISING ASHELL HAVING A CIRCULAR RIM PORTION AND AN OUTER FACE PORTION, SAID RIMPORTION INITIALLY BEING OF A DIAMETER THAT IS SLIGHTLY SMALLER THAN ACORE HOLE IN WHICH THE PLUG IS TO BE USED, THE OUTER FACE OF SAID SHELLHAVING A PROJECTION THEREON THAT IS CONFIGURATED TO RECEIVE A TOOL BYMEANS OF WHICH SAID ASSEMBLY MAY BE HELD AND MANIPULATED, AN EXPANDERDISK THAT IS OF A DIAMETER TO INITIALLY FIT WITHIN SAID RIM PORTION INSLIPFIT RELATION, SAID EXPANDER DISK BEING CONCAVE AND ADAPTED TO BESEATED WITHIN SAID RIM PORTION WITH THE CONCAVE FACE THEREOF TOWARD SUCHSHELL PORTION, A BRACE DISK ADAPTED TO BE SEATED WITHIN SAID SHELLBETWEEN SAID EXPANDER DISK AND THE OUTER FACE PORTION OF SAID SHELL,SAID BRACE DISK HAVING A CENTRAL PORTION ADAPTED TO CONTACT THE REARFACE OF THE CENTRAL PORTION OF SAID PROJECTION AND HAVING AN OUTERANNULAR AREA ADAPTED TO CONTACT THAT PART OF SAID OUTER FACE PORTIONSURROUNDING SAID PROJECTION, THERE BEING A CENTRAL OPENING IN SAIDEXPANDER DISK, SAID BRACE DISK AND SAID OUTER PROJECTION, A LARGE HEADEDBOLT EXTENDING THROUGH SAID EXPANDER DISK, SAID BRACE DISK AND SAIDOUTER PROJECTION, SAID BOLT HAVING THREADS THEREON, AND AN ACORN NUTADAPTED TO BE ENGAGED UPON SAID THREADS SUCH THAT THE TIGHTENING OF SAIDNUT CAUSES SAID EXPANDER DISK TO BE DEFORMED RADIALLY OUTWARDLY FOREXPANDING SAID RIM PORTION INTO INTIMATE CONTACT WITH THE WALL OF A COREHOLE.